Education

Post Doctorate, Biochemistry & Biophysics, University of California School of MedicinePost Doctorate, Biochemistry & Biophysics, University of California School of Medicine

Education/Training Program Affiliations

Department of Biochemistry PhDInterdisciplinary Graduate Program in Molecular and Cellular BiologyInterdisciplinary Graduate Program in Translational BiomedicineMedical Scientist Training Program

Research Summary

Our laboratory investigates the biochemistry of actin and the actin binding proteins that modulate its function within the cell. In particular, we are interested in the conformational changes in actin necessary for its polymerization, the forces that stabilize actin monomers within the actin filament, and the manner in which actin filament modulating proteins such as cofilin, Arp2/3 complex and profilin carry out their roles. Our approach is to use yeast actin and the yeast actin cytoskeleton as a model system. Based on hypotheses concerning actin function and actin dynamics, we make mutant actin constructs using site-directed mutagenesis, express the actin in yeast as the only actin in the cell, and determine phenotypes associated with the actin mutation such as altered growth rate, altered endocytosis, and altered actin deposition. We then purify the actin and determine its in vitro behavior using a series of biochemical and biophysical approaches such as electron microscopy and fluorescence spectroscopy. We then try to correlate the effects of the mutations we observe in vitro with the phenotypes associated with these mutations in vivo. With this basic system, we are currently focusing on two projects. We have shown that although the proteins are 90% identical, muscle and yeast actins display distinct differences in their kinetics and ability to interact with different actin binding proteins that can have a substantial effect on actin filament dynamics. To investigate the basis for these differences, we have made a set of yeast/muscle hybrid actins with one yeast half and one muscle half to try to determine which part of the actin is responsible for the behavioral differences seen between the two parent actins. Second, it has been found that six different actin mutations cause autosomal dominant hearing loss in humans. We have cloned each of these into yeast actin and are assessing the effects of these mutations in vivo and in vitro with the goal of gaining insight into altered actin interactions that might result in deafness.

All Publications

Rubenstein P,
Wen K.
Mutant vascular actin is a TAAD misbehaving..
Proceedings of the National Academy of Sciences of the United States of America.
2015 August 4. 112(31):9500-1.
[PubMed]

Orlova A,
Shvetsov A,
Galkin V,
Kudryashov D,
Rubenstein P,
Egelman E,
Reisler E.
Actin-destabilizing factors disrupt filaments by means of a time reversal of polymerization.
Proceedings of the National Academy of Sciences of the United States of America.
2004 December. 101(51):17664-8.
[PubMed]

Sheff D,
Rubenstein P.
Identification of N-acetylmethionine as the product released during the NH2-terminal processing of a pseudo-class I actin.
The Journal of Biological Chemistry.
1989 July. 264(19):11491-6.
[PubMed]

Cass K,
Clark E,
Rubenstein P.
Is the onset of actin histidine methylation under development control in the chick embryo.
Archives of Biochemistry and Biophysics.
1983 September. 225(2):731-9.
[PubMed]

Rubenstein P,
Strominger J.
Enzymatic synthesis of cytidine diphosphate 3,6-dideoxyhexoses. 8. Studies of the properties of E3 and its role in the formation of cytidine diphosphate-4-keto-3,6-dideoxyglucose.
The Journal of Biological Chemistry.
1974 June. 249(12):3782-88.
[PubMed]